Hands-on Activity: Traveling Sound
Educational Standards :
Pre-Req Knowledge (Return to Contents)
A basic understanding of the phases of matter: liquids, solids and gases.
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
Introduction/Motivation (Return to Contents)
Sound engineers are especially interested in the way sound travels. Can you hear as well when you sit in the back of the class as when you sit in the front? What about in the assembly hall or gymnasium? On the playground? Can you think of other times when you cannot hear as well as someone else? What happened? How about in a movie theater? What do engineers do so that the sound quality is good for everyone in a movie theater? (Possible answers: Add speakers around the room, curtains, carpet the walls, cone-shaped theaters act like a megaphone and help to direct sound waves further.)
Which is louder — walking on carpet or on tile? It is quieter on carpet because the carpet absorbs the sound energy. Sound energy, light energy and other types of energy, need molecules to travel through and vibrate, but sometimes sound energy is absorbed by an object or material. Engineers use this idea when designing rooms that are meant to be quiet. Have you ever noticed how the walls of a movie theater are covered with carpet or fabric? This is to prevent echoing of the sound system. Sometimes when you are in an empty room, your voice echoes or sounds hollow. This is because an empty room has no materials in it that might absorb the sound energy, so the sound bounces off the hard walls, back at you. This makes it hard to hear clearly.
Do you think sound energy can travel through air? Of course it can! That is how sound energy travels when you talk to a friend. How about water? Can you hear sound travel under water? How about a solid? Can sound move through a solid object? Engineers want to know if sound can travel through solids, liquids and gases so they can develop ways to send messages to people all over the world. Can you imagine how great sound would be if it could travel anywhere?
Understanding the properties of sound and how sound waves travel helps engineers determine the best room shape and construction materials when designing libraries, classrooms, sound recording studios, concert halls and theatres. Room shape and materials can impact how sound waves travel since sound waves bounce off different object in different ways. In this activity, we are going to study how sound waves travel through liquids, solids and gases, and think about how engineers might use this information.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Before the Activity
With the Students
- Hum with your mouth and nose open.
- Hum with your mouth open and nose closed.
- Hum with your mouth closed and nose open.
- Hum with your mouth and nose closed.
Attachments (Return to Contents)
Troubleshooting Tips (Return to Contents)
This activity can be very loud. Ask the students to not disturb others while they learn and have fun.
Assessment (Return to Contents)
Prediction: Ask students if they think sound can move through solid, liquid, and gas. If so what are some examples? (Possible examples: Students may recall talking under water or using tin can and string telephones.)
Activity Embedded Assessment
Worksheet: Have the students use the Traveling Sounds Worksheet to guide them in the activity and as a place to record their observations. Review their answers to gauge their mastery of the subject.
T oss-a-Question Ask students to independently think of an answer to the question below and write it on a half sheet of paper. Have students wad up and toss the paper to another team member who then adds his/her answer idea. After all students have written down ideas, have them toss the paper wad to another team, who reads the answers aloud to the class. Discuss answers with the class.
Neighbor Check: Have the students compare their activity observations with a neighbor. Are they the same or different? Have each team report some of their similar and dissimilar observations to the rest of the class.
Engineering Design: The supply of air on Earth is running out! Several futuristic cities for human habitation are being designed either underwater or deep inside mountains. Have each student group become a city planning engineering team and draw a communication system for sending emergency messages between the new cities. Make sure to illustrate and describe how the sound energy (message) will move through air, water or solid rock.
Activity Extensions (Return to Contents)
To bring some humor to the activity, ask each student to hum a small part of his/her favorite song while feeling his/her throat. Have each student alternate between having his/her nose and mouth open or closed while humming non-stop. Why does the sound change depending on whether you close your nose or mouth? What happens if you block your ears? What does this activity teach us about sound? (Answer: Sound vibrations must travel through air for us to hear them. Like a musical instrument [perhaps a recorder or flute], if you change the holes where sound escapes, it changes the pitch, but not the frequency/vibrations of the sound.)
If a metal bowl is used during the activity, the vibrations from the objects colliding underwater vibrate the bowl, creating the illusion that the bowl is being struck. Have students draw the vibrations in the bowl on a piece of paper. Do the vibrations change if the objects are tapped together increasing softly?
Have students think about different forms of communications. Does sound travel most often through solids, liquids or gases? Have students poll their friends, family and neighbors to solicit their ideas.
Activity Scaling (Return to Contents)
References (Return to Contents)
Dictionary.com. Lexico Publishing Group, LLC. Accessed December 19, 2005. (Source of some vocabulary definitions, with some adaptation.) http://www.dictionary.com
ContributorsSharon Perez, Natalie Mach, Malinda Schaefer Zarske, Denise Carlson
Copyright© 2005 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.